Content for  TS 29.232  Word version:  16.0.0

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1  ScopeWord‑p. 10
The present document describes the protocol to be used on the Media Gateway Controller (MGC) - Media Gateway (MGW) interface. The Media Gateway Controllers covered in this specification are the MSC server and the GMSC server. The basis for this interface profile is the H.248.1 [10] protocol as specified in ITU-T. The usage of this protocol is described in TS 23.205 and TS 29.205 for BICC circuit switched core network, in TS 23.231 and TS 29.231 for SIP-I circuit switched core network.
This profile includes the support for the enhanced MSC server to provide access to IMS Centralised services as described in TS 23.292 and thus the procedures related to this interface are described in TS 29.292. As a result the interworking with SIP and the associated MGW control procedures described in TS 29.163 for the interworking between BICC/ISUP circuit switched core network and IP Multimedia core network are incorporated.
This specification describes the changes to H.248 which are needed to handle 3GPP specific traffic cases. This is done by using the H.248 standard extension mechanism. In addition certain aspects of the base protocol H.248 are not needed for this interface and thus excluded by this profile.

2  References

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
  • References are either specific (identified by date of publication, edition number, version number, etc.) or non specific.
  • For a specific reference, subsequent revisions do not apply.
  • For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
TS 23.153: "Out of band transcoder control; Stage 2".
TS 23.205: "Bearer independent circuit-switched core network; Stage 2".
TS 24.008: "Mobile radio interface Layer 3 specification; Core network protocols; Stage 3".
TS 25.415: "UTRAN Iu interface user plane protocols".
TS 28.062: "Inband Tandem Free Operation (TFO) of speech codecs; Service description; Stage 3".
TS 29.007: "General requirements on interworking between the Public Land Mobile Network (PLMN) and the Integrated Services Digital Network (ISDN) or Public Switched Telephone Network (PSTN)".
TS 29.205: "Application of Q.1900 series to Bearer Independent circuit-switched network architecture; Stage 3".
TS 29.415: "Core Network Nb interface user plane protocols".
TS 48.008: "Mobile Switching Centre - Base Station System (MSC BSS) interface; Layer 3 specification".
ITU-T Recommendation H.248.1 (05/2002): "Gateway control protocol: Version 2" including the Corrigendum1 for Version 2 (03/04).
ITU-T Recommendation Q.2210 (1996): "Message transfer part level 3 functions and messages using the services of ITU-T Recommendation Q.2140".
RFC 2960:  "Stream control transmission protocol".
TS 29.202: "Signalling System No. 7 (SS7) signalling transport in core network; Stage 3".
ITU-T Recommendation H.248.8 (09/2005): "Error codes and service change reason description".
ITU-T Recommendation H.248.10 (07/2001): "Media gateway resource congestion handling package".
TS 26.103: "Speech codec list for GSM and UMTS".
ITU-T Recommendation H.248.2 (01/2005): "Facsimile, text conversation and call discrimination packages".
TS 26.226: "Cellular text telephony; Transport of text in the voice channel".
ITU-T Recommendation T.140 (02/1998): "Protocol for multimedia application text conversation".
TS 25.413: "UTRAN Iu interface RANAP signalling".
TS 25.414: "UTRAN Iu interface data transport and transport signalling".
TS 23.078: "Customized Applications for Mobile network Enhanced Logic (CAMEL); Stage 2".
ITU-T Recommendation Q.1950 (12/2002): "Bearer independent call bearer control protocol".
ITU-T Recommendation Q.765.5 (04/2004): "Signalling system No. 7 - Application transport mechanism: Bearer Independent Call Control (BICC)".
ITU-T Recommendation G.711 (11/1988): "Pulse code modulation (PCM) of voice frequencies".
TS 26.102: "Mandatory speech codec; AMR speech codec; Interface to Iu, Uu and Nb".
TS 23.014: "Support of Dual Tone Multi-Frequency (DTMF) signalling".
ITU-T Recommendation H.248.7 (03/2004): "Generic Announcement Package".
TS 32.421: "Subscriber and equipment trace: Trace concepts and requirements ".
TS 32.422: "Subscriber and equipment trace: Trace control and configuration management".
TS 32.423: "Subscriber and equipment trace: Trace data definition and management".
TS 29.414: "Core Network Nb data transport and transport signalling".
ITU-T Recommendation X.213 (11/95): "Information technology - Open systems interconnection - Network Service Definitions".
[34]  Void
TS 43.045: "Technical Realization Of Facsimile Group 3 service - Transparent".
ITU-T Recommendation H.248.36 (09/2005): "Hanging Termination Detection Package".
TS 23.172: : "Technical realization of Circuit Switched (CS);multimedia service UDI/RDI fallback and service modification;Stage 2".
TS 33.210: : "3G Security; Network Domain Security; IP Network Layer Security.
TS 43.068: " Voice Group Call Service (VGCS); Stage 2".
TS 43.069: " Voice Broadcast Service (VBS); Stage 2".
ITU-T Recommendation X.690: "ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)".
ITU-T Recommendation H.248.41 (05/2006): " IP Domain Connection package".
TS 23.003: "Numbering, addressing and identification".
RFC 3309:  "Stream Control Transmission Protocol (SCTP) Checksum Change"
ITU-T Recommendation H.248.14 (03/2009):"Inactivity timer package"
[46]  Void
[47]  Void
[48]  Void
[49]  Void
[50]  Void
TS 29.332: "Media Gateway Control Funtion (MGCF) - IM Media Gateway; Mn Interface".
RFC 3556:  "Session Description Protocol (SDP) Bandwidth Modifiers for RTP Control Protocol (RTCP) Bandwidth".
RFC 4566:  "SDP: Session Description Protocol".
TS 23.231: "SIP-I based circuit switched core network; stage 2".
RFC 4040:  "RTP Payload Format for a 64 kbit/s Transparent Call".
[56]  Void
TS 29.231: "Application of SIP-I Protocols to Circuit Switched (CS) core network architecture; Stage 3".
TS 32.407: "Telecommunication Management; Performance Management (PM) Performance measurements Core Network (CN) Circuit Switched (CS) domain".
TS 23.292: "IP Multimedia Subsystem (IMS) Centralized Services; Stage 2".
TS 29.292: "Interworking between the IP Multimedia (IM) Core Network (CN) subsystem and MSC Server for IMS Centralized Services (ICS)".
TS 29.163: "Interworking between the IM CN subsystem and CS networks - Stage 3".
[62]  Void
[63]  Void
RFC 2198:  "RTP Payload for Redundant Audio Data".
TS 48.103: "Base Station System - Media GateWay (BSS-MGW) interface; User Plane transport mechanism".
ITU-T Recommendation H.248.57 (06/2008): "Gateway control protocol: RTP Control Protocol Package".
ITU-T Recommendation H.248.43 (06/2008): "Gateway control protocol: Gate Management and Gate Control packages".
ITU-T Recommendation H.248.53 (06/2008) inclusive Revision 1 (03/2009): "Gateway control protocol: Traffic management packages".
ITU-T Recommendation H.248.52 (06/2008): "Gateway control protocol: QoS support packages".
ITU-T Recommendation H.248.40 (01/2007): "Gateway control protocol: Application Data Inactivity Detection package".
ITU-T Recommendation H.248.41 Amendment 1 (06/2008): "Gateway control protocol: IP domain connection package: IP Realm Availability Package".
RFC 2216:  "Network Element Service Specification Template".
[74]  Void
[75]  Void
[76]  Void
TS 26.114: "IP Multimedia Subsystem (IMS); Multimedia Telephony; Media handling and interaction".
TS 22.153: "Multimedia Priority Service".
ITU-T Recommendation H.248.82 (03/2013): "Gateway control protocol: Explicit Congestion Notification Support".
RFC 5245:  "Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal for Offer/Answer Protocols".
ITU-T Recommendation H.248.50 (09/2010) Corrigendum 1 (02/12): "Gateway control protocol: NAT traversal toolkit packages".
TS 24.229: "IP Multimedia Call Control Protocol based on SIP and SDP".
TS 26.445: "Codec for Enhanced Voice Services (EVS); Detailed Algorithmic Description".
RFC 5939:  "Session Description Protocol (SDP) Capability Negotiation".
ITU-T Recommendation H.248.80 (01/2014): "Gateway control protocol: Usage of the revised SDP offer/answer model with ITU-T H.248".

3  Definitions, symbols and abbreviationsWord‑p. 13

3.1  Definitions

For the purposes of the present document, the following terms and definitions apply:
context (H.248):
association between a number of Terminations
The context describes the topology (who hears/sees whom) and the media mixing and/or switching parameters if more than two terminations are involved in the association.
package (H.248):
different types of gateways may implement terminations which have differing characteristics
Variations in terminations are accommodated in the protocol by allowing terminations to have optional properties. Such options are grouped into packages, and a termination may realise a set of such packages.
termination (H.248):
logical entity on an MGW which is the source and/or sink of media and/or control streams
A termination is described by a number of characterising properties, which are grouped in a set of descriptors which are included in commands. Each termination has a unique identity (TerminationID).
termination property (H.248):
used to describe terminations
Related properties are grouped into descriptors. Each termination property has a unique identity (PropertyID).
For the purposes of the present document, the following terms and definitions as defined in TS 29.292 apply:
ICE lite
Full ICE

3.2  SymbolsWord‑p. 14
For the purposes of the present document, the following symbols apply:
Interface between the RNS and the core network. It is also considered as a reference point.
Interface between the server and the media gateway.

3.3  Abbreviations

For the purposes of the present document, the following abbreviations apply:
Bearer Independent Call Control
Congestion Experienced
Explicit Congestion Notification
Enhanced Voice Services
Interactive Connectivity Establishment
SS7 MTP3 - User Adaptation Layer
Media Gateway Controller
Multimedia Priority Service
Message Transfer Part layer 3
Request For Comment; this includes both discussion documents and specifications in the IETF domain
Stream Control Transmission Protocol
Session Description Protocol
SDP Capability Negotiation
Session Traversal Utilities for NAT
Tandem Free Operation
Transcoder Free Operation

4  UMTS capability set

The support of the Mc interface capability set shall be identified by the Mc profile and support of this profile shall then be indicated in ServiceChange procedure via the ServiceChangeProfile parameter as defined in H.248.1 [10] and clarified in section 4.2. The mandatory parts of this profile shall be used in their entirety. Failure to do so will result in a non-standard implementation.
ITU-T Recommendation H.248.1 [10] shall be the basis for thisprofile. The compatibility rules for packages, signals, events, properties and statistics and the H.248 protocol are defined in ITU-T Recommendation H.248.1 [10] Their use or exclusion for this interface is clarified in clause 12.

4.1  Profile Identification |R5|

For Profile Identification see Annex C.1.

4.2  Profile Registration |R5|

The following description is based on H.248.1 profile registration procedure with some clarifications. The reply to the ServiceChange Request containing the SCP parameter indicates if the MSC Server supports the requested profile or if it does not support it and wants to propose an alternative profile. The profile (name and version) is only returned in the reply if the MGC cannot support the specified profile in the ServiceChangeRequest. The returned reply shall indicate the profile and version supported or "NoProfile" if no profile is supported. Upon reception of a profile in the reply, if the MGW supports the indicated profile, it shall issue a new ServiceChange Request with the agreed profile to explicitly confirm the acceptance of the profile to the MGC ; otherwise, if the MGW does not support the indicated profile, it may continue the registration or re-registration procedure by issuing a new ServiceChange Request with an alternative profile ; until such procedure is successfully completed the MGW shall remain out of service. In the instance that the MGW did not indicate a profile in the original ServiceChangeRequest and the MGC returned a profile in the reply, the MGW shall issue a new ServiceChangeRequest with the appropriate profile or "NoProfile" if no profile is supported. If the profile is not returned the MGC shall use the capabilities specified by the Profile indicated in the service change request.

5  Naming conventionsWord‑p. 15

5.1  MGC/MGW naming conventions

For definition see Annex C.11.

5.2  Termination names

For definition see Annex C.6.1.

6  Topology descriptor

For definition see Annex C.7.8.

7  Transaction timers

For definition see Annex C.10.

8  Transport

Each implementation of the Mc interface should provide the appropriate protocol options: MTP3B as defined in ITU-T Recommendation Q.2210 [11] (for ATM signalling transport) or SCTP as defined in RFC 2960 and as updated by RFC 3309 (for IP signalling transport) and in the case where the signalling relation consists of both ATM signalling transport and IP signalling transport the M3UA protocol layer (TS 29.202) shall be added to SCTP to provide interworking. M3UA layer may also be added to SCTP for pure IP signalling transport. IPsec shall not be used by MSC Server or MGW for the Mc interface. Normally the Mc interface lies within a single operator's secure domain. If this is not the case then a Za interface (Security Gateway deploying IPSec) may be required, however this is a separate logical function/entity and thus is not attributed to Mc profile, the MSC Server or the MGW; for further details see TS 33.210. For further definition see Annex C.12.

9  Multiple Virtual MG.

If an MGW is connected to more than one (G)MSC, the MGW shall fulfil the requirements outlined in the subclause "Multiple virtual MGW" in ITU-T Recommendation H.248.1 [10].

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